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HURRICANE DENNIS DISCUSSION NUMBER 25
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT SUN AUG 29 1999
THE LATEST AIR FORCE RESERVE RECONNAISSANCE PLANE REPORTED A MINIMUM
CENTRAL PRESSURE OF 963 MB...A 4 MB DROP OVER THE LAST 6 HRS. THE
EYE REMAINS RATHER RAGGED IN APPEARANCE...ABOUT 35 NMI IN DIAMETER
...WITH THE STRONGEST CONVECTION HAS NOW ROTATED AROUND THE SOUTHERN
SIDE OF THE CENTER. THE MOST RECENT HRD WIND ANALYSIS...WHICH
INCORPORATES STEPPED FREQUENCY MICROWAVE RADIOMETER DATA FROM THE
NOAA P-3 AIRCRAFT...SUPPORTS MAINTAINING THE 90 KTS INTENSITY. WITH
THE IMPRESSIVE UPPER-LEVEL OUTFLOW AND THE WARM GULF STREAM WATERS
THE FORECAST STILL CALLS FOR SOME STRENGTHENING...100 KT BY 24 HRS.
REGARDLESS...THE LARGE SIZE OF THIS HURRICANE AN EXTENSIVE PORTION
OF THE NORTH CAROLINA COAST WILL BE IMPACTED.
POSITION ESTIMATES FROM RECONNAISSANCE AND RADAR SUGGEST THAT DENNIS
IS NOW MOVING ON A NORTH-NORTHEAST HEADING...020/12 KT. THE SYNOPTIC
-BASED REASONING BEHIND THE TRACK FORECAST REMAINS UNCHANGED FROM
THE LAST PACKAGE AS THE MID-LEVEL TROUGH MOVING THROUGH THE
NORTHEAST U.S. STEERS DENNIS ON A GENERAL NORTHEASTWARD TRACK
THROUGH 36 HRS. BEYOND 36 HRS...SOME OF THE DYNAMIC GUIDANCE
SUGGESTS THAT THE TROUGH WILL BY-PASS THE HURRICANE LEAVING DENNIS
JUST OFF THE MID ATLANTIC COAST BY 72 HRS. THEREAFTER...THERE IS
CONSIDERABLE UNCERTAINTY REGARDING THE FUTURE TRACK OF DENNIS.
BLOCKING HIGH...WHICH SHOULD REPLACE THE NORTHEAST U.S. TROUGH...
MAY CAUSE THE CYCLONE TO MEANDER OFF THE COAST NEAR THE END OF THE
PERIOD AND BEYOND. THE OFFICIAL FORECAST TRACK IS SHIFTED SLIGHTLY
TO THE LEFT OF THE PREVIOUS ADVISORY MAINLY DUE TO THE INITIAL
MOTION.
AFTER COORDINATION WITH NATIONAL WEATHER SERVICE OFFICES...THE
HURRICANE WATCH AND TROPICAL STORM WARNING FROM EDISTO BEACH SOUTH
CAROLINA SOUTHWARD WILL BE DISCONTINUED.
GUINEY
FORECAST POSITIONS AND MAX WINDS
INITIAL 30/0300Z 32.5N 77.8W 90 KTS
12HR VT 30/1200Z 33.7N 76.8W 95 KTS
24HR VT 31/0000Z 34.7N 75.2W 100 KTS
36HR VT 31/1200Z 35.5N 73.5W 100 KTS
48HR VT 01/0000Z 36.0N 72.0W 100 KTS
72HR VT 02/0000Z 36.0N 70.5W 100 KTS
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